President Donald Trump's reason for blacklisting Huawei revolves around national security fears that the company's technology could be used for Chinese government-sponsored spying. The move, which also prevents Huawei from buying parts and components from American companies, could prove to have a hugely detrimental effect on Huawei's production of its popular smartphones and laptops.

That ban prevents companies like Facebook, Google, and Dropbox from reaching the country's over 800 million internet users. Still, it doesn't mean that China doesn't factor into the equation for those companies: Facebook, for example, saw an estimated $5 billion in ad revenue from Chinese-based companies in 2018, making the country the company's second largest ad market, according to AdAge.

Particular queries on Google, including those related to politics, have long been censored in China. Google.cn, the company's China-based search engine, was shut down in 2010 following disputes over censorship of search queries. Google's family of apps - including Gmail and Google Maps - have went offline multiple times, including in November 2012 and December 2014.

Snapchat

Matt Winkelmeyer/Getty Images

When it was first blocked: It's unclear when Snapchat was initially banned in China, but the social platform does have a small office in the country to work on Spectacles, Snap's camera-equipped smart sunglasses.

Reddit

Tumblr

When it was first blocked:May 2016, although pages containing political and pornographic content have been heavily censored in China before then.

Pinterest

Hollis Johnson/Business Insider

When it was first blocked: March 2017, around the time when China was hosting its annual "Two Sessions" political gathering.

Slack

Getty

When it was first blocked: The timeline of when Slack was first blocked in China is not clear, but access to the messaging app has been "somewhat inconsistent" for years, according to the company itself.

Quora

When it was first blocked: The popular Q&A site was first blocked in China in August 2018.

Medium

Diarmuid Greene/Web Summit via Sportsfile

When it was first blocked: The blogging site was unavailable in the country from April 2016.

Wikipedia

Getty

When it was first blocked: Wikipedia's Chinese-language edition has been blocked for good since 2015, but China barred all language versions of Wikipedia more recently: this May.

Vimeo

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When it was first blocked: The video site went down in China pretty early, in October 2009.

Flickr

SmugMug/YouTube

When it was first blocked: The photo site went behind the "Great Firewall" in June 2007, just a few years after Yahoo bought it. Nowadays, SmugMug owns Flickr, but it doesn't appear like the site's situation in China has changed at all.

SoundCloud

AP Photo/Mark Lennihan

When it was first blocked: The music-sharing service was first blocked in September 2013. Since then, it's been blocked in China intermittently, including in May 2015.

DuckDuckGo

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When it was first blocked: The privacy-focused search engine was blocked in September 2014.

Dailymotion

Reuters/Jean-Paul Pelissier

When it was first blocked: Like several popular video-sharing sites, Dailymotion is blocked in China, although it's not clear when it went into effect.